Two intriguing properties of the superalgebra SBMS\(_4\)  should be stressed. First, nonlinear terms appear in the brackets of the asymptotic generators, as in AdS\(_3\)  supergravity [1]}, but we have not explored whether these nonlinear terms could be absorbed through redefinitions. Second, another infinite-dimensional fermionic symmetry arises, generated by \(Q_\sigma \) . It would be worthwhile to understand the reason behind its emergence, which might perhaps be related to sub-leading soft theorems through the corresponding Ward identities (see [2]} for the connection between soft theorems and asymptotic symmetries).
